Question

At what displacement is the $KE$ of a particle performing $SHM$ of amplitude $10cm$ is three times its $PE$ ?

• A. $2.5cm$
• B. $5cm$
• C. $7.5cm$
• D. $10cm$

Answer 1

The correct option is B $5cm$

$KE=3PE$
$\frac{1}{2}m{\omega }^2(A^2-x^2)=3\times \frac{1}{2}m{\omega }^2{x}^2$
$A^2=4x^2$
$x=\frac{A}{2}$
$x=\frac{10}{2}$
$x=5$ cm